1. Field of the Invention
The present invention relates to a UV light-permeable glass and an article comprising the same. More particularly, the present invention relates to a glass which is permeable to UV light and comprises a fluorine-doped synthetic quartz glass and an article made of such glass.
2. Description of the Related Art
Hitherto, as a UV light-permeable glass, only synthetic quartz glass is known. However, the synthetic quartz glass has various defect absorption depending on methods for producing the same. Main defect absorptions are specific defect absorptions due to atomic groups having free radicals such as Si--Si, Si., Si--O--O--Si and Si--O--O. (see J. Appl. Phys. 65(12), 15, June 1989, and Physical Review B, 38, 17 (1988)).
As a glass material which reduces such defects and is excellent in permeability in UV range, a synthetic quartz glass containing OH groups in a high concentration such as 100 to 1000 ppm is commercially available.
However, when the synthetic quartz glass having the high OH concentration is irradiated with a high energy UV light such as an excimer laser for a long time, other problems such as generation of fluorescence and formation of new absorption bands arise, so that such quartz glass does not have a long term reliability.